WASHINGTON - Twenty-one senators asked the Environmental Protection Agency for more information Thursday about an internal paper that reportedly concludes that the gasoline additive MTBE may cause cancer. Key elements of the document, which has not been made public, surfaced as lawmakers considered whether to shield the makers of MTBE from product liability lawsuits as a result drinking water contamination in at least 36 states. MTBE, which was put into gasoline to cut air pollution, has been banned in several states because of complaints that it adds a foul smell and turpentine-like taste to drinking water when it leaks into...